Today there are many automated dialog systems in operation that serve many purposes, such as for customer care. Because they limit human involvement, such systems save millions of dollars in labor costs. Examples of such systems are shown in U.S. Pat. Nos. 5,675,707, 5,860,063, 6,044,337, and 6,173,261, and U.S. patent application Ser. No. 08/943,944, filed Oct. 3, 1997, Ser. No. 09/699,494, 09/699,495, and 09/699,496 all filed Oct. 31, 2000, and Ser. No. 09/712,192 and 09/712,194, both filed Nov. 15, 2000, each of which is incorporated by reference herein in its entirety.
While it has recently become possible to build spoken dialog systems that interact with users in real-time in a range of domains, systems that support conversational natural language are still subject to a large number of language understanding errors. Endowing such systems with the ability to reliably distinguish language understanding errors from correctly understood communications might allow them to correct some errors automatically or to interact with users to repair them, thereby improving the system's overall performance.